Filtering messages in a distributed virtual world based on virtual space properties

ABSTRACT

A system and method are provided for filtering messages propagated among peer servers in a distributed virtual world. Each peer server hosts a virtual space within the virtual world and filters messages based on the state and properties of its virtual space. In order to propagate messages, messages originating in a virtual space are first provided to the peer server hosting that virtual space. The peer server propagates the messages to one or more of its neighboring peer servers hosting virtual spaces that neighbor its virtual space in the virtual world. These peer servers may then propagate the messages to their neighboring peer servers. When propagating the messages, the peer servers either apply filter rules to the messages or append filter rules to the messages in order to filter the messages based on the state and properties of the virtual spaces hosted by the peer servers.

FIELD OF THE INVENTION

The present invention relates to a distributed virtual world and more specifically relates to filtering messages propagated among peer servers in a distributed virtual world.

BACKGROUND OF THE INVENTION

Decentralized Peer-to-Peer (P2P) virtual worlds are an emerging technology wherein a number of peer servers host virtual spaces within the virtual world. If virtual objects within the virtual world have auras and Areas of Interest (AOIs) that span multiple virtual spaces, messages such as event messages, content messages, and content update messages originating from virtual objects in a virtual space hosted by a peer server must be propagated to other peer servers hosting other virtual spaces in the virtual world in which the messages are relevant. Likewise, messages originating in virtual spaces hosted in other peer servers that are of interest to virtual objects within the virtual space hosted by the peer server must be propagated to the peer server. Thus, there is a need for a system and method for efficiently propagating messages in a decentralized P2P virtual world.

SUMMARY OF THE INVENTION

The present invention relates to filtering messages propagated among peer servers in a distributed virtual world such as a Peer-to-Peer (P2P) virtual world. In general, each peer server hosts a cell, or virtual space, within the virtual world and filters messages based on the state and properties of its virtual space. In order to propagate messages throughout the P2P virtual world, messages originating in a specific virtual space are first provided to the peer server hosting that virtual space. If the scopes of the messages extend beyond that virtual space, the peer server propagates the messages to one or more of its neighboring peer servers hosting virtual spaces that neighbor the virtual space hosted by the peer server. These peer servers may then propagate the messages to their neighboring peer servers. The process continues such that the messages are propagated throughout the virtual world. When propagating the messages, the peer servers either apply filter rules to the messages or append filter rules to the messages in order to filter the messages based on the state and properties of the virtual spaces hosted by the peer servers. For example, a peer server hosting a virtual space having a large building may filter visual messages or append filters to visual messages that are affected, or blocked, by the large building.

Those skilled in the art will appreciate the scope of the present invention and realize additional aspects thereof after reading the following detailed description of the preferred embodiments in association with the accompanying drawing figures.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

The accompanying drawing figures incorporated in and forming a part of this specification illustrate several aspects of the invention, and together with the description serve to explain the principles of the invention.

FIG. 1 illustrates a system 10 for implementing a Peer-to-Peer (P2P) virtual world according to one embodiment of the present invention;

FIG. 2 illustrates a number of virtual spaces of the virtual world hosted by corresponding peer servers according to one embodiment of the present invention;

FIG. 3 illustrates a number of peer servers hosting the virtual spaces of FIG. 2 according to one embodiment of the present invention;

FIG. 4 illustrates the operation of a peer server issuing an advertisement/subscription (ad/sub) message according to one embodiment of the present invention;

FIG. 5 illustrates the operation of a neighboring peer server in response to receiving the ad/sub message from an originating peer server according to one embodiment of the present invention;

FIGS. 6A and 6B are a more detailed illustration of the operation of the neighboring peer server to process the ad/sub message according to one embodiment of the present invention;

FIG. 7 is a more detailed illustration of the operation of the neighboring peer server to propagate the ad/sub message according to one embodiment of the present invention;

FIGS. 8A-8D graphically illustrate process of issuing and responding to an ad/sub message in order to establish message flow paths for messages produced and consumed by virtual objects within a virtual space hosted by a peer server according to one embodiment of the present invention;

FIG. 9 is a block diagram of a peer server according to one embodiment of the present invention;

FIG. 10 illustrates a filtering scheme for filtering irrelevant messages due to the state or properties of a virtual space according to one embodiment of the present invention;

FIG. 11 illustrates the filtering process according to one embodiment of the present invention;

FIGS. 12A-12D graphically illustrate the filtering process according of FIG. 11;

FIG. 13 is a block diagram of a peer server implementing the filtering scheme according to one embodiment of the present invention;

FIGS. 14A-14C are a more detailed illustration of the filtering process according to one embodiment of the present invention;

FIG. 15 illustrates the operation of the Relevancy Determination Subsystem (RDS) of FIGS. 13 and 14A-14C according to one embodiment of the present invention;

FIGS. 16A-16B illustrate the filtering process according to another embodiment of the present invention; and

FIG. 17 is a block diagram of one of the network devices of FIG. 1 according to one embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The embodiments set forth below represent the necessary information to enable those skilled in the art to practice the invention and illustrate the best mode of practicing the invention. Upon reading the following description in light of the accompanying drawing figures, those skilled in the art will understand the concepts of the invention and will recognize applications of these concepts not particularly addressed herein. It should be understood that these concepts and applications fall within the scope of the disclosure and the accompanying claims.

FIG. 1 illustrates an exemplary system 10 for implementing a Peer-to-Peer (P2P) virtual world incorporating the message propagation scheme of the present invention. The virtual world may be, for example, a virtual world similar to Second Life or a Massively Multiplayer Online Role Playing Game (MMORPG). It should be noted that while the description herein focuses on a P2P virtual world, the present invention is equally applicable to any type of distributed virtual world. In general, the system 10 includes a number of network devices 12-1 through 12-N and optionally 14 communicatively coupled by a network 16. The network 16 may be a Wide Area Network (WAN), Local Area Network (LAN), or a combination thereof and may include wired components, wireless components, or both wired and wireless components. For example, the network 16 may be the Internet. The network devices 12-1 through 12-N and 14 communicate in a P2P fashion via a P2P overlay network built on top of the network 16.

The network devices 12-1 through 12-N and 14 may each be, for example, a personal computer; a mobile device such as a Personal Digital Assistant (PDA) or mobile telephone; a mobile gaming device similar to a Nintendo DS® or PSP® (PlayStation Portable®); a gaming console; or the like. The network devices 12-1 through 12-N include virtual world peer servers 18-1 through 18-N (hereinafter “peer servers 18-1 through 18-N”). The peer servers 18-1 through 18-N may be implemented in software, hardware, or a combination thereof. As discussed below, each of the peer servers 18-1 through 18-N hosts a cell of the virtual world, where the cell is also referred to herein as a virtual space. Users associated with the peer servers 18-1 through 18-N may customize or create their virtual spaces by, for example, creating buildings, altering the terrain or landscape, defining weather or weather patterns, or the like. In one embodiment, a new cell is created for each of the peer servers 18-1 through 18-N when they are first registered with the system 10. When, for example, the peer server 18-1 is offline, the corresponding cell of the virtual world may cease to exist until the peer server 18-1 is again online. Alternatively, when the peer server 18-1 is offline, the cell of the virtual world typically hosted by the peer server 18-1 may be temporarily hosted by one of the other peer servers 18-2 through 18-N. In another embodiment, a central system assigns the cells of the virtual world to the peer servers 18-1 through 18-N. The assignment may be static such that, for example, the peer server 18-1 typically hosts a particular cell of the virtual world. When the peer server 18-1 is offline, the corresponding cell of the virtual world may cease to exist or be temporarily hosted by one of the other peer servers 18-2 through 18-N. As another alternative, the central system may dynamically assign the cells of the virtual world to the peer servers 18-1 through 18-N as they come online and go offline.

In this example, the network devices 12-1, 12-2, 12-3, and 12-N also include virtual world clients 20-1 through 20-M, which are hereafter referred to as clients 20-1 through 20-M. Note that, in this example, one or more network devices such as the network device 12-4 may include a peer server but not a client. The clients 20-1 through 20-M may be implemented in software, hardware, or a combination thereof. The clients 20-1 through 20-M enable users of the network devices 12-1, 12-2, 12-3, and 12-N to view and interact with the virtual world. More specifically, in the preferred embodiment, the users are enabled to control corresponding avatars to move within and interact with the virtual world.

In addition, in this example, the network device 14 includes a virtual world client 22, which is hereafter referred to as a client 22. Note that while only the network device 14 is illustrated, the system 10 may include any number of network devices having a client but not a peer server. The client 22 may be implemented in software, hardware, or a combination thereof. The client 22 enables a user of the network device 14 to view and interact with the virtual world.

FIG. 2 illustrates a portion of the virtual world hosted by corresponding peer servers. In this example, eighteen cells, or virtual spaces, VS1-VS18 are illustrated, where each of the cells VS1-VS18 are hexagonally shaped and of equal size. However, the present invention is not limited thereto. Each of the virtual spaces of the virtual world may be any shape and size. In this example, an avatar of a user Alice is currently within the virtual space VS1, an avatar of a user Bob is currently within the virtual space VS11, and an avatar of user Charles is currently within the virtual space VS12.

The virtual spaces VS1-VS18 are hosted by peer servers 18-1 through 18-18, which are illustrated in FIG. 3. The virtual space VS1 is hosted by the peer server 18-1, the virtual space VS2 is hosted by the peer server 18-2, etc. The peer servers 18-1 through 18-18 are communicatively coupled by the P2P overlay network as illustrated. Using the peer server 18-1 as an example, the peer server 18-1 is communicatively coupled to each of the peer servers 18-2 through 18-7 hosting neighboring virtual spaces VS2-VS7 in the virtual world via corresponding P2P communication channels. Note that the peer servers 18-2 through 18-7 are also referred to herein as the neighboring peer servers of the peer server 18-1. In a similar fashion, the peer servers 18-2 through 18-18 are communicatively coupled to their neighboring peer servers via P2P communication channels.

In addition, because the avatar of the user Alice is currently within the virtual space VS1, the corresponding client, which in this example is the client 20-X, is communicatively coupled to the peer server 18-1 hosting the virtual space VS1. While within the virtual space VS1, the client 20-X interacts with the virtual world via the peer server 18-1. Likewise, because the avatar of the user Bob is currently within the virtual space VS11, the corresponding client, which in this example is the client 20-Y, is communicatively coupled to the peer server 18-11 hosting the virtual space VS11. While within the virtual space VS11, the client 20-Y interacts with the virtual world via the peer server 18-11. Lastly, because the avatar of the user Charles is currently within the virtual space VS12, the corresponding client, which in this example is the client 20-Z, is communicatively coupled to the peer server 18-12 hosting the virtual space VS12. While within the virtual space VS12, the client 20-Z interacts with the virtual world via the peer server 18-12. Note that X, Y, and Z may each be any integer from 1 to M. Further, note, in another embodiment, one of the avatars may alternatively be associated with the client 22 of the network device 14.

If, for example, the user Alice moves her avatar from the virtual space VS1 to the virtual space VS2, the client 20-X disconnects from the peer server 18-1 hosting the virtual space VS1 and connects to the peer server 18-2 hosting the virtual space VS2. Then, while Alice's avatar is in the virtual space VS2, the client 20-X interacts with the virtual world via the peer server 18-2.

FIG. 4 illustrates the operation of a peer server in establishing message flow according to one embodiment of the present invention. The peer server 18-1 is used as an example. First, the peer server 18-1 obtains interest expressions for each virtual object in its virtual space VS1 (step 100). An interest expression for a virtual object includes information identifying message types produced by the virtual object and corresponding Areas of Interest (AOIs) and information identifying message types consumed by the virtual object and corresponding auras. The aura and AOI may vary depending on message type. If so, the interest expression includes information defining the AOI of the virtual object with respect to each message type consumed by the virtual object and the aura of the virtual object with respect to each message type produced by the virtual object. Note that rather than including information explicitly defining an AOI for a message type, an interest expression may include information from which the AOI for the message type may be extrapolated. For example, for visual messages from a virtual object such as a building, the interest expression may include information such as, for example, the size of the building. The AOI of the building with respect to the visual messages may then be extrapolated by the peer server 18-1 based on the size of the building or extrapolated by subsequent peer servers as messages related to the building are propagated. The ad/sub message may include information identifying the location of the building as well as the size of the building especially if, for example, the AOI is extrapolated by subsequent peer servers.

As used herein, aura is an area of the virtual world over which messages of a message type produced by a virtual object are relevant. For example, for messages of a visual type, a virtual object may have an aura corresponding to an area of the virtual world in which the virtual object can been seen. Likewise, for messages of an audio type, a virtual object may have an aura corresponding to an area of the virtual world in which sounds made by the virtual object can be heard. The aura of a message type may be expressed as, for example, a set of vectors each specifying a set of coordinates or a starting point, a direction, and a distance. The combination of the set of vectors using known geometric algorithms describes an area, which is the aura of the message type. As another example, in a virtual world that is a fractal generated maze, the aura may be expressed in terms of a starting point on the fractal and the limit to which the fractal equation should be applied from that point. Other ways to express the aura will be apparent to one of ordinary skill in the art upon reading this disclosure and are within the scope of the present invention. Further, the manner in which the aura is expressed may vary depending on the characteristics of the virtual world.

In contrast, an AOI is an area of the virtual world relevant to a virtual object from a consumer perspective. For example, for an avatar consuming messages of a visual type, the AOI of the avatar may correspond to an area of the virtual world that can be seen by the avatar. Thus, the AOI may correspond to the line-of-sight of the avatar. The AOI of a message type may be expressed as, for example, a set of vectors each specifying a set of coordinates or a starting point, a direction, and a distance. The combination of the set of vectors using known geometric algorithms describes an area, which is the AOI of the message type. As another example, in a virtual world that is a fractal generated maze, the AOI may be expressed in terms of a starting point on the fractal and the limit to which the fractal equation should be applied from that point. Other ways to express the AOI will be apparent to one of ordinary skill in the art upon reading this disclosure and are within the scope of the present invention. Further, the manner in which the AOI is expressed may vary depending on the characteristics of the virtual world.

A message type may be, for example, an event message type, a content message type, or a content update message type. The message types may be further classified by sub-type. Thus, in one embodiment, a message type includes a primary message type and a sub-type. The primary message type may be, for example, an event message type, a content message type, or a content update message type. The sub-types may further define the message types. For example, a sub-type may be an audio sub-type, a visual sub-type, an avatar movement sub-type, a social interaction sub-type, or a virtual space state sub-type. Thus, messages related to avatar movement may be classified as the event/avatar movement message type. Likewise, messages related to weather conditions in a virtual space may be classified as the event/virtual space state message type.

In addition, custom message types may be defined for a virtual object. The custom message types may be particularly beneficial where users are enabled to customize virtual objects and/or the virtual spaces hosted by their associated peer servers 18-1 through 18-N.

The interest expressions for the virtual objects may be actively obtained by the peer server 18-1, provided to the peer server 18-1 from some source such as the virtual objects, known by the peer server 18-1 in advance, or any combination thereof. For example, for an avatar, the interest expression for the avatar may be provided to the peer server 18-1 by the client associated with the avatar or provided to the peer server 18-1 by the avatar itself. Alternatively, if the avatar just entered the virtual space hosted by the peer server 18-1 from the virtual space hosted by, for example, the peer server 18-2, the peer server 18-2 may provide the interest expression for the avatar to the peer server 18-1. In the case of static virtual objects or virtual objects that do not leave the virtual space of the peer server 18-1, the interest expressions for these virtual objects may be known to the peer server 18-1. The above examples are not intended to limit the scope of the present invention. Other schemes for obtaining the interest expressions of the virtual objects within the virtual space hosted by the peer server 18-1 may be apparent to one of ordinary skill in the art upon reading this disclosure and are to be considered within the scope of the present invention.

While the process of obtaining the interest expressions of the virtual objects is illustrated as a single step, one of ordinary skill in the art will readily appreciate that the peer server 18-1 continually or periodically performs the process in order to accommodate changing interest expressions and mobile virtual objects entering and leaving the virtual space hosted by the peer server 18-1.

The peer server 18-1 then generates an advertisement/subscription (ad/sub) message (step 102). The ad/sub message is also referred to herein as a message flow path setup message. While the ad/sub message is discussed herein as a single message, the peer server 18-1 may alternatively generate and issue separate advertisement and subscription messages. Further, while the ad/sub message discussed herein is an aggregate ad/sub message for each of the virtual objects in the virtual space hosted by the peer server 18-1, the present invention is not limited thereto. The peer server 18-1 may alternatively issue separate advertisement and subscription messages or ad/sub messages for each virtual object in the virtual space hosted by the peer server 18-1 or for groups of virtual objects within the virtual space hosted by the peer server 18-1.

In one embodiment, the ad/sub message includes an advertisement record for each message type produced by one or more of the virtual objects within the virtual space hosted by the peer server 18-1. Each advertisement record includes the corresponding message type and an aggregate scope corresponding to an aggregate or combination of the auras of the one or more virtual objects within the virtual space hosted by the peer server 18-1 that produce messages of the corresponding message type. The aggregate scope may be expressed as, for example, a set of vectors each specifying a set of coordinates or a starting point, a direction, and a distance. The combination of the set of vectors using known geometric algorithms describes an area, which is the aggregate scope of the advertisement record. As another example, in a virtual world that is a fractal generated maze, the aggregate scope may be expressed based on a fractal equation. As another example, the aggregate scope may be represented by conditional logic or expressions such as, for example, “within 500 ft from point A OR within 750 ft from point B.” Note that rather than including the aggregate aura, the scope may alternatively include information from which the aggregate aura can be extrapolated. For example, for visual messages from a virtual object such as a building, the scope of the corresponding advertisement record may including information describing, for example, a size of the building. The scope or aura of the visual messages may be extrapolated based on the size of the building.

In one embodiment, when aggregating the auras of the one or more virtual objects within the virtual space hosted by the peer server 18-1 that produce messages of a particular message type, the peer server 18-1 may optionally adjust the aggregate scope to compensate for various factors such as, for example, movement of mobile virtual objects. For example, for a message type produced by an avatar, the peer server 18-1 may adjust the aura of the avatar when aggregating the aura with the auras of other virtual objects producing that message type or adjust the aggregate scope for the message type to include a margin that compensates for frequent movement of the avatar. More specifically, the peer server 18-1 may adjust the aura of the avatar or the aggregate scope for the message type such that the aggregate scope is expanded by some margin. For instance, the aura or aggregate scope may be expanded in all directions or expanded in a predicted direction of movement for the avatar.

In addition, each advertisement record may include information or metadata describing the one or more virtual objects producing the corresponding message type and/or one or more references to information or metadata describing the virtual objects producing the corresponding message types. In addition to describing the virtual objects themselves, the metadata may also include or describe the states of the virtual objects such as, for example, the locations of the virtual objects producing the corresponding message type.

The ad/sub message also includes a subscription record for each message type consumed by one or more of the virtual objects within the virtual space hosted by the peer server 18-1. Each subscription record includes the corresponding message type and an aggregate scope corresponding to an aggregate or combination of the AOIs of the one or more virtual objects within the virtual space hosted by the peer server 18-1 that consume messages of the corresponding message type. The aggregate scope may be expressed as, for example, a set of vectors each specifying a set of coordinates or a starting point, a direction, and a distance. The combination of the set of vectors using known geometric algorithms describes an area, which is the aggregate scope of the subscription record. As another example, in a virtual world that is a fractal generated maze, the aggregate scope may be expressed based on a fractal equation. As another example, the aggregate scope may be represented using a conditional expression.

In one embodiment, when aggregating the AOIs of the one or more virtual objects within the virtual space hosted by the peer server 18-1 that consume messages of a particular message type, the peer server 18-1 may optionally adjust the aggregate scope to compensate for various factors such as, for example, the movement of mobile virtual objects. For example, for a message type produced by an avatar, the peer server 18-1 may adjust the AOI of the avatar when aggregating the AOI with the AOIs of other virtual objects consuming that message type or adjust the aggregate scope for the message type to compensate for frequent movement of the avatar. More specifically, the peer server 18-1 may adjust the AOI of the avatar or the aggregate scope for the message type such that the aggregate scope is expanded.

In addition, each subscription record may include additional criteria for identifying virtual objects producing the corresponding message types that are of interest to the peer server 18-1 and/or the virtual objects within the virtual space hosted by the peer server 18-1 having an interest in the corresponding message type. For example, with respect to avatars producing messages of the corresponding message type, the criteria may include demographic or biological information describing the associated users or the like. Other criteria will be apparent to one of ordinary skill in the art upon reading this disclosure. Note that the criteria may vary depending on the details of the virtual world.

Note that the ad/sub message may also include an advertisement record for a new virtual object. The advertisement record may then trigger the other peer servers having an interest in the new virtual object to obtain content or other information and possibly an application needed to render the new virtual object from the peer server 18-1 or some other source. This may be particularly beneficial where users are enabled to customize their own virtual spaces. The ad/sub message may also include advertisement records for messages produced by the new virtual object and subscription records for messages consumed by the new virtual object.

While the discussion herein focuses on the embodiment where each of the advertisement and subscription records includes a scope, the present invention is not limited thereto. As an alternative, the ad/sub message may include a global scope applicable to all of the advertisement and subscription records. As another alternative, the ad/sub message may include a scope applicable to all of the advertisement records and a scope applicable to all of the subscription records.

When generating the ad/sub message, the peer server 18-1 may use conditional logic or expressions to represent or combine multiple records into a single rule. For example, rather than having a separate advertisement record for each message type produced, the peer server 18-1 may combine all advertisement records into a single conditional expression, or rule, or combine subsets of the records into corresponding conditional expressions, or rules.

Note that while the following discussion focuses on generating an ad/sub message including advertisement and subscription records for each virtual object within the virtual space hosted by the peer server 18-1, the present invention is not limited thereto. For example, the first ad/sub message generated and issued by the peer server 18-1 may be a complete ad/sub message including an advertisement record for each message type produced by any virtual object within the virtual space hosted by the peer server 18-1 and a subscription record for each message type consumed by any virtual object within the virtual space hosted by the peer server 18-1. However, subsequent ad/sub messages generated and issued by the peer server 18-1 may be complete ad/sub messages or, alternatively, may be partial ad/sub messages reflecting changes since the previous ad/sub message was generated and issued by the peer server 18-1.

In addition to the advertisement and subscription records, the ad/sub message may include unsubscribe messages enabling the peer server 18-1 to unsubscribe to message types that were previously of interest to the peer server 18-1. For example, the peer server 18-1 may desire to unsubscribe to a message type if the peer server 18-1 no longer has an interest in the message type.

Once the ad/sub message is generated, the peer server 18-1 sends the ad/sub message to one or more of its neighboring peer servers 18-2 through 18-7 (step 104). In one embodiment, the peer server 18-3 propagates the ad/sub message in an expanding ring search (ERS) manner, where a time-to-live (TTL) may be defined in order to enforce an absolute upper limit on the propagation of the ad/sub message.

More specifically, in one embodiment, the peer server 18-1 sends the ad/sub message to all of its neighboring peer servers 18-2 through 18-7. In another embodiment, the peer server 18-1 generates copies of the ad/sub message for each of the neighboring peer servers 18-2 through 18-7 and filters the copies of the ad/sub message based on the scopes of the advertisement and subscription messages. More specifically, for the neighboring peer server 18-2, advertisement records that have scopes that do not extend into the virtual space of the neighboring peer server 18-2 are filtered from the copy of the ad/sub message to be provided to the neighboring peer server 18-2. Note that the records that have already been processed with respect to the neighboring peer server 18-2 may also be filtered. Likewise, subscription messages whose scopes do not extend into the virtual space of the neighboring peer server 18-2 are filtered from the copy of the ad/sub message to be provided to the neighboring peer server 18-2. If the filtered copy of the ad/sub message to be provided to the neighboring peer server 18-2 is empty, then no ad/sub message is provided to the neighboring peer server 18-2. Otherwise, the filtered copy of the ad/sub message is provided to the neighboring peer server 18-2. Likewise, the copies of the ad/sub message for the other neighboring peer servers 18-3 through 18-7 are filtered and provided to the other neighboring peer servers 18-3 through 18-7.

As discussed below, the neighboring peer servers 18-2 through 18-7 then process the ad/sub message, propagate the ad/sub message if appropriate, and respond to the ad/sub message. Thus, the peer server 18-1 receives responses to the ad/sub message from one or more of the neighboring peer servers 18-2 through 18-7 (step 106). The responses from the neighboring peer servers 18-2 through 18-7 identify message types of interest or, more specifically, identify message types from the advertisement records in the ad/sub message that are to be routed to them. Using the peer server 18-2 as an example, the response from the peer server 18-2 identifies message types from the advertisement records in the ad/sub message that are of interest to the peer server 18-2. The message types are of interest to the peer server 18-2 if they are consumed by virtual objects in the virtual space hosted by the peer server 18-2 or of interest to one or more neighboring peer servers of the peer server 18-2 to which the peer server 18-2 propagated the ad/sub message. If none of the message types from the advertisement records in the ad/sub message are of interest to the peer server 18-2, the peer server 18-2 may provide a response indicating that none of the message types from the advertisement records are of interest or, alternatively, may not respond to the ad/sub message. Likewise, the other neighboring peers 18-3 through 18-7 provide responses to the ad/sub message.

Based on the responses to the ad/sub message from the neighboring peer servers 18-2 through 18-7, the peer server 18-1 then updates its routing table such that messages produced by the virtual objects in the virtual space hosted by the peer server 18-1 are routed only to the ones of the neighboring peer servers 18-2 through 18-7 expressing an interest in that message type (step 108). In one embodiment, for each message type from the advertisement records in the ad/sub message, the routing table includes an entry in the form of:

-   -   <message type><message recipient(s)><virtual object ID(s)>         where the virtual object IDs are IDs of the virtual objects in         the virtual space hosted by the peer server 18-1 that are         producers of the message type. Alternatively, the routing table         may be maintained such that any message originating in the         virtual space hosted by the peer server 18-1 of the         corresponding message type is to be routed according to this         entry. The message recipients are one or more of the neighboring         peer servers 18-2 through 18-7 that have expressed an interest         in the message type. Thereafter, when a virtual object produces         a message, the peer server 18-1 routes the message according to         the routing table such that the message is routed only to ones         of the neighboring peer servers 18-2 through 18-7 that have         expressed an interest in that message type.

As discussed below in detail, with respect to the subscription records in the ad/sub message, message flow paths from others of the peer servers 18-2 through 18-N hosting virtual objects producing message types identified in the subscription records are identified as the ad/sub message is propagated among the peer servers 18-2 through 18-N.

FIG. 5 illustrates the operation of a peer server, such as the peer server 18-3, receiving the ad/sub message from the peer server 18-1 according to one embodiment of the present invention. The peer server 18-1 is also referred to herein as the originating peer server 18-1. First, the peer server 18-3 receives the ad/sub message from the originating peer server 18-1 (step 200). The peer server 18-3 then processes the ad/sub message to determine whether to subscribe to any of the message types identified by the advertisement records in the ad/sub message and, based on the subscription records, whether any message types produced by virtual objects in the virtual space hosted by the peer server 18-3 are to be routed to the originating peer server 18-1 (step 202).

More specifically, for each advertisement record, the peer server 18-3 determines whether any of the virtual objects in the virtual space hosted by the peer server 18-3 are consumers of the corresponding message type. If so, the peer server 18-3 determines whether any of the virtual objects that are consumers of the message type are within the aggregate scope, or aggregate aura, for the advertisement record or, alternatively, whether any portion of the virtual space hosted by the peer server 18-3 is within the aggregate scope, or aggregate aura, for the advertisement record. If so, the peer server 18-3 adds an entry to a response to the ad/sub message to be thereafter provided to the originating peer server 18-1 subscribing to messages of the message type from the originating peer server 18-1. As a result, the response to the ad/sub message includes entries subscribing to each of the message types identified by the advertisement records of the ad/sub message that are consumed by one or more of the virtual objects in the virtual space hosted by the peer server 18-3.

In addition, for each subscription record, the peer server 18-3 determines whether messages of the corresponding message type are produced by one or more virtual objects within the virtual space hosted by the peer server 18-3. If so, the peer server 18-3 determines whether any of the virtual objects producing the corresponding message type are within the aggregate scope, or aggregate AOI, for the subscription record or, alternatively, if any portion of the virtual space hosted by the peer server 18-3 is within the aggregate scope, or aggregate AOI, for the subscription record. If so, the peer server 18-3 updates its routing table such that messages of the corresponding message type produced by virtual objects within the aggregate scope for the subscription record are routed to the originating peer server 18-1.

In addition, the peer server 18-3 propagates the ad/sub message, or a filtered copy thereof, to one or more of its neighboring peer servers 18-2, 18-4, and 18-8 through 18-10 (step 204). In one embodiment, there is a pre-established default routing scheme for the ad/sub message. Assuming an efficient routing scheme, the peer server 18-3 may propagate the ad/sub message, or a filtered copy thereof, only to the ones of its neighboring peer servers 18-2, 18-4, and 18-8 through 18-10 that have not or will not receive the ad/sub message from another peer server according to the default routing scheme. However, the present invention is not limited thereto. Any routing scheme may be used. Further, the propagation does not have to be efficient. In other words, duplicate ad/sub messages may be permitted and simply ignored. Also note that the ad/sub message may be used to establish the default routing scheme, or propagation path, for subsequent ad/sub messages. Note that while peer servers 18-2 and 18-4 are also neighbors of the peer server 18-3, the ad/sub message need not be propagated to them because they are also neighbors of the originating peer server 18-1 and have therefore already received the ad/sub message from the originating peer server 18-1.

More specifically, in one embodiment, the peer server 18-3 creates a copy of the ad/sub message for each of the neighboring peer servers 18-8 through 18-10 and optionally filters the copies of the ad/sub messages based on the scopes of the advertisement and subscription records. Using the peer server 18-8 as an example, the peer server 18-3 may filter the copy of the ad/sub message for the peer server 18-8 to remove advertisement and subscription records whose aggregate scopes do not extend into the virtual space hosted by the peer server 18-8. Likewise, the copies of the ad/sub message for the other neighboring peer servers 18-9 and 18-10 are filtered. The filtered copies of the ad/sub message are then provided to neighboring peer servers 18-8 through 18-10.

With respect to the subscription records, when propagating the copies of the ad/sub message to the neighboring peer servers 18-8 through 18-10, the peer server 18-3 updates its routing table such that messages from its neighboring peer servers of the message types identified by the subscription records are routed to the originating peer server 18-1. More specifically, using the peer server 18-8 as an example, the peer server 18-3 updates its routing table such that messages of the message types identified in the subscription records in the copy of the ad/sub message provided to the peer server 18-8 that are thereafter received from the peer server 18-8 are routed to the originating peer server 18-1. As discussed below, the neighboring peer server 18-8 updates its routing table in response to the ad/sub message such that messages originating from virtual objects in its virtual space or received from its neighboring peer servers that are of the message types identified in the subscription records are routed to the peer server 18-3, which in turn routes the messages to the originating peer server 18-1

The peer server 18-3 then receives responses to the ad/sub message from the neighboring peer servers 18-8 through 18-10 (step 206). The responses identify ones of the message types from the advertisement records of the ad/sub message, or filtered copy thereof, that are of interest to the neighboring peer servers 18-8 through 18-10. Message types are of interest to the neighboring peer servers 18-8 through 18-10 if the neighboring peer servers 18-8 through 18-10 host virtual objects within their virtual spaces that consume the message types or if the neighboring peer servers of the peer servers 18-8 though 18-10 express an interest in the message types in response to propagation of the ad/sub message from the peer servers 18-8 through 18-10 to those neighboring peer servers. Using the peer server 18-8 as an example, the response from the peer server 18-8 includes a number of entries, records, or information otherwise identifying message types from advertisement records of the copy of the ad/sub message provided to the peer server 18-8 that are of interest to the peer server 18-8.

After receiving the responses, the peer server 18-3 updates its routing table such that messages from the originating peer server 18-1 are routed to ones of the neighboring peer servers 18-8 through 18-10 that have expressed an interest in those message types (step 208). In one embodiment, the peer server 18-3 generates an entry in its routing table for each message type from the originating peer server 18-1 in the form of:

-   -   <preceding peer server><message type><message origin><succeeding         peer(s)>         where, in this example, the preceding peer is the originating         peer server 18-1 and the one or more succeeding peers are the         ones of the neighboring peer servers 18-8 through 18-10 that         have expressed an interest in that message type in response to         the ad/sub message. The message origin may be information         identifying one or more originating peer servers, which in some         scenarios may be different than the preceding peer server, to         which this routing table entry applies. Note that the entries in         the routing table may include additional information.

In addition, the peer server 18-3 generates and sends an aggregate response to the originating peer server 18-1 (step 210). The aggregate response is the aggregate or combination of the responses from the neighboring peer servers 18-8 through 18-10 and the response of the peer server 18-3 generated in step 202. As such, the aggregate response identifies the message types from the advertisement records in the ad/sub message received from the originating peer server 18-1 in which the peer server 18-3 has an interest. Again, the peer server 18-3 has an expressed interest in message types consumed by virtual objects in the virtual space hosted by the peer server 18-3 as well as message types of interest to the neighboring peer servers 18-8 through 18-10. As discussed above, upon receiving the aggregate response to the ad/sub message, the originating peer server 18-1 updates its routing table such that messages of the message types in which the peer server 18-3 has expressed an interest are routed to the peer server 18-3.

In a similar fashion, the other neighboring peer servers 18-2 and 18-4 through 18-7 of the originating peer server 18-1 process, propagate, and respond to the ad/sub message from the originating peer server 18-1. As a result, message flow paths for the message types produced by the virtual objects in the virtual space hosted by the originating peer server 18-1 are defined. In addition, as a result of the subscription records in the ad/sub message, message flow paths for message types produced by virtual objects in the virtual spaces hosted by the other peer servers 18-2 through 18-N that are of interest to one or more of the virtual objects in the virtual space hosted by the originating peer server 18-1 are defined from the corresponding ones of the peer servers 18-2 through 18-N to the originating peer server 18-1. Likewise, the other peer servers 18-2 through 18-N issue their own ad/sub messages in order to define message flow paths for message types produced and consumed by the virtual objects within their virtual spaces.

FIGS. 6A and 6B are a more detailed illustration of the processing step 202 of FIG. 5 according to one embodiment of the present invention. More specifically, in order to process the ad/sub message from the originating peer server 18-1, the peer server 18-3 first determines whether it has reached the last record in the ad/sub message (step 300). Note that step 300 is preferably not performed the first iteration through the processing loop since the ad/sub message includes at least one record. If the peer server 18-3 has reached the last record in the ad/sub message, the process ends (step 302). If the last record in the ad/sub message has not been reached, the peer server 18-3 then gets the next record, which for the first iteration will be the first record, in the ad/sub message (step 304).

The peer server 18-3 then determines whether the record is an advertisement record (step 306). If so, the peer server 18-3 determines whether any of the virtual objects in the virtual space hosted by the peer server 18-3 have registered an interest for the message type identified by the advertisement record (step 308). More specifically, in one embodiment, the peer server 18-3 may determine whether any of the virtual objects in its virtual space are consumers of the message type based on the interest expressions of the virtual objects that have been registered with the peer server 18-3. If one or more of the virtual objects in the virtual space hosted by the peer server 18-3 is a consumer of the message type, the peer server 18-3 then determines whether the virtual objects that are consumers of the message type are within the aggregate scope or, optionally, expected to be within the aggregate scope for the advertisement record (step 310).

If none of the virtual objects in the virtual space hosted by the peer server 18-3 have an interest in the message type or if none of the virtual objects in the virtual space having an interest in the message type are within or expected to be within the aggregate scope for the advertisement record, the peer server 18-3 may optionally create a latent entry or latent advertisement record (step 312). The latent entry generally corresponds to the advertisement record and is stored such that the peer server 18-3 may subscribe to the message type of the advertisement record in the future if one or more virtual objects in its virtual space have a registered interest in the message type and are within or expected to be within the aggregate scope of the advertisement record. If one or more of the virtual objects in the virtual space have a registered interest in the message type and are within or expected to be within the aggregate scope of the advertisement record, the peer server 18-3 adds a corresponding subscription record to the response to the ad/sub message to be provided to the originating peer server 18-1 (step 314).

Returning to step 306, if the record is not an advertisement record, the peer server 18-3 determines whether the record is a subscription record (step 316). If so, the peer server 18-3 determines whether any of the virtual objects in the virtual space hosted by the peer server 18-3 are producers of the corresponding message type (step 318). If so, the peer server 18-3 determines whether any of the virtual objects that produce the message type are within the aggregate scope, or aggregate AOI, of the subscription record (step 320). If so, the peer server 18-3 updates its routing table such that messages of the message type produced by the virtual objects in its virtual space and within the aggregate scope of the subscription record are routed to the originating peer server 18-1 (step 322).

Then, whether or not any of the virtual objects in the virtual space of the peer server 18-3 are interested in the message type and, if so, are within the aggregate scope of the subscription record, the process proceeds to step 324. In step 324, the peer server 18-3 updates its routing table such that messages of the message type identified by the subscription record received from one or more of its neighboring peer servers 18-8 through 18-10 to which the peer server 18-3 propagates the ad/sub message are thereafter routed to the originating peer server 18-1 (step 324). Thus, whether or not any virtual objects in the virtual space hosted by the peer server 18-3 are consumers of the message type, the peer server 18-3 still updates its routing table if it propagates the ad/sub message to one or more of its neighboring peer servers 18-8 through 18-10 such that messages received from those neighboring peer servers of that message type are routed to the originating peer server 18-1. At this point, the process returns to step 300 and is repeated for the next record in the ad/sub message.

Returning to step 316, if the record is not a subscription record, the peer server 18-3 determines whether the record is an unsubscribe record (FIG. 6B, step 326). In general, an unsubscribe record may be issued by the originating peer server 18-1 when the originating peer server 18-1 no longer has an interest in the corresponding message type. For example, the originating peer server 18-1 may issue an unsubscribe record when an avatar that is a consumer of a message type leaves the virtual space of the originating peer server 18-1 and the originating peer server 18-1 has no other virtual objects consuming the message type and the originating peer server 18-1 does not have an interest in the message type for purposes of routing. If the record is not an unsubscribe record, the process returns to step 300. If the record is an unsubscribe record, the peer server 18-3 determines whether any of the virtual objects in its virtual space are producers of the corresponding message type (step 328). If so, the peer server 18-3 updates its routing table such that messages of the corresponding message type produced by virtual objects within its virtual space are no longer routed to the originating peer server 18-1 (step 330). In addition, whether or not virtual objects producing the corresponding message type are within the virtual space of the peer server 18-3, the peer server 18-3 updates its routing table such that messages of the corresponding message type received from its neighboring peer servers 18-8 through 18-10 are no longer routed to the originating peer server 18-1 (step 332). The process then returns to step 300 of FIG. 6A and is repeated for the next record in the ad/sub message.

FIG. 7 is a more detailed illustration of the propagation step 204 of FIG. 5 according to one embodiment of the present invention. First, the peer server 18-3 generates a copy of the ad/sub message from the originating peer server 18-1 for one of its neighboring peer servers 18-8 through 18-10 (step 400). Note that it may not be necessary to create a copy of the ad/sub message if no modifications are necessary before propagation. In this example, the originating peer server 18-3 first generates a copy of the ad/sub message for the peer server 18-8. Copies of the ad/sub message for the other neighboring peer servers 18-9 and 18-10 are generated and processed in subsequent iterations of the loop.

The peer server 18-3 then filters the advertisement and subscription records in the copy of the ad/sub message based on the aggregate scope of each of the records (step 402). More specifically, advertisement records having an aggregate scope, or aggregate aura, that does not extend into the virtual space hosted by the peer server 18-8 are removed from the copy of the ad/sub message to be provided to the peer server 18-8. Likewise, subscription records having an aggregate scope, or aggregate AOI, that does not extend into the virtual space hosted by the peer server 18-8 are also removed from the copy of the ad/sub message to be provided to the peer server 18-8.

After filtering, the peer server 18-3 determines whether the filtered copy of the ad/sub message is empty (step 404). If not, the peer server 18-3 sends the filtered copy of the ad/sub message to the peer server 18-8 (step 406). Note that, at this point, the peer server 18-3 may update its routing table such that messages of the message types identified by the subscription records in the filtered copy of the ad/sub message that are thereafter received from the peer server 18-8 are routed to the originating peer server 18-1. Then, whether or not the filtered copy of the ad/sub message is empty, the peer server 18-3 determines whether the peer server 18-8 is the last neighboring peer server (step 408). If so, the process ends (step 410). If not, the process returns to step 400 and is repeated for the remaining neighboring peer servers 18-9 and 18-10.

FIGS. 8A through 8D illustrate the advertisement and subscription process according to one embodiment of the present invention. For clarity and ease of discussion, FIGS. 8A through 8D illustrate the process with respect to the cells, or virtual spaces, of the virtual world. However, as will be appreciated by one of ordinary skill in the art, the actual message flow is between the peer servers 18-1 through 18-18 and the clients 20-X, 20-Y, and 20-Z associated with the illustrated avatars.

FIG. 8A illustrates an initial state where an avatar of a user Bob is within virtual space VS11, which is hosted by peer server 18-11 (FIG. 3). Likewise, an avatar of a user Charles is within virtual space VS12, which is hosted by peer server 18-12 (FIG. 3). The peer servers 18-11 and 18-12 have already established the message flow path for messages consumed and produced by the avatars of Bob and Charles.

FIG. 8B illustrates the virtual world at a subsequent point in time where an avatar of a user Alice is within virtual space VS1, which is hosted by the peer server 18-1 (FIG. 3). As a result, the peer server 18-1 hosting the virtual space VS1, which is hereafter referred to as the originating peer server 18-1, issues an ad/sub message to its neighboring peer servers 18-2 through 18-7 in the manner discussed above. The ad/sub message includes an advertisement record for each message type produced by the avatar of Alice and a subscription record for each message type consumed by the avatar of Alice. The ad/sub message is then propagated among the peer servers 18-2 through 18-N based on the aggregate scope of each of the advertisement and subscription records in the ad/sub message.

As illustrated, the ad/sub message is propagated to the peer server 18-4 hosting the virtual space VS4, which in turn propagates the ad/sub message, or a filtered copy thereof, to the peer server 18-11 hosting the virtual space VS11. Similarly, the ad/sub message is propagated to the peer server 18-5 hosting the virtual space VS5, which in turn propagates the ad/sub message, or a filtered copy thereof, to the peer server 18-12 hosting the virtual space VS12.

FIG. 8C illustrates the responses to the ad/sub message according to one embodiment of the present invention. In this example, ones of the peer servers 18-2 through 18-N in receipt of the ad/sub message and not having an interest in one or more of the message types identified by the advertisement records do not respond. However, the present invention is not limited thereto. As illustrated, because the avatar of the user Bob is a consumer of all or at least some of the message types produced by the avatar of the user Alice identified in the advertisement records in the ad/sub message, the peer server 18-11 hosting the virtual space VS11 sends a response to the peer server 18-4 hosting the virtual space VS4 expressing an interest in one or more of the message types identified by the advertisement records that are consumed by the avatar of the user Bob. As a result, the peer server 18-4 hosting the virtual space VS4 updates its routing table and sends a response to the peer server 18-1 expressing an interest in the message types identified in the response from the peer server 18-11. In response, the originating peer server 18-1 updates its routing table such that messages of the message types in which the peer server 18-4 has expressed an interest are thereafter routed to the peer server 18-4, which in turn routes those messages to the peer server 18-11.

Likewise, because the avatar of the user Charles is a consumer of all or at least some of the message types produced by the avatar of the user Alice identified in the advertisement records in the ad/sub message, the peer server 18-12 hosting the virtual space VS12 sends a response to the peer server 18-5 hosting the virtual space VS5 expressing an interest in one or more of the message types identified by the advertisement records that are consumed by the avatar of the user Charles. As a result, the peer server 18-5 hosting the virtual space VS5 updates its routing table and sends a response expressing an interest in the message types identified in the response from the peer server 18-12. In response, the originating peer server 18-1 updates its routing table such that messages of message types in which the peer server 18-5 has expressed an interest are thereafter routed to the peer server 18-5, which in turn routes those messages to the peer server 18-12.

With respect to the message types consumed by the avatar of the user Alice, the peer server 18-4 hosting the virtual space VS4 updates its routing table in response to the ad/sub message such that messages of the message types identified by the subscription records in the ad/sub message subsequently received from its neighboring peer servers such as the peer server 18-11 are routed to the originating peer server 18-1. The peer server 18-11 updates its routing table in response to the ad/sub message such that messages produced by the avatar of the user Bob of the message types identified by the subscription records are routed to the peer server 18-4 hosting the virtual space VS4, which will then route those messages to the peer server 18-1. In a similar fashion, the peer servers 18-5 and 18-12 establish a message flow path for the message types produced by the avatar of the user Charles that are consumed by the avatar of the user Alice from the peer server 18-12 to the peer server 18-1 via the peer server 18-5.

FIG. 8D illustrates the resultant message flow paths for the propagation of messages consumed and produced by the avatars of the users Alice, Bob, and Charles. Messages produced by the avatar of the user Alice are provided from the associated client to the peer server 18-1 hosting the virtual space VS1. The peer server 18-1 then routes the messages to the peer servers 18-4 and 18-5 based on its routing table, and the peer servers 18-4 and 18-5 then route the messages to the peer servers 18-11 and 18-12, respectively, based on their routing tables. The peer server 18-11 then routes the messages to the client associated with the avatar of the user Bob. Likewise, the peer server 18-12 routes the messages of interest to the client associated with the avatar of the user Charles.

In a similar fashion, messages produced by the avatar of the user Bob that are of message types consumed by the avatar of the user Alice are routed from the peer server 18-11 to the peer server 18-1 via the peer server 18-4. The peer server 18-1 then routes the messages to the client associated with the avatar of the user Alice. Likewise, messages produced by the avatar of the user Charles that are of message types consumed the avatar of the user Alice are routed from the peer server 18-12 to the peer server 18-1 via the peer server 18-5. The peer server 18-1 then routes the messages to the client associated with the avatar of the user Alice.

Note that either in response to an advertisement record for the avatar of the user Alice, in response to receiving advertisement records for message types produced by the avatar of the user Alice, or in response to receiving, for example, visual messages from the avatar of the user Alice, the clients associated with the avatars of the users Bob and Charles may obtain content or information and optionally an application needed to render the avatar of the user Alice.

Another feature that may be provided by the present invention is predictive ad/sub messages. More specifically, referring to FIG. 8D, if Bob controls his avatar such that it begins to move toward the virtual space VS10, the peer server 18-11 may calculate an estimated time of arrival in the virtual space VS10 and issue a predictive ad/sub message specifically addressed to the peer server 18-10 enabling the peer server 18-10 to subscribe to message types consumed by Bob's avatar and/or message types produced by Bob's avatar in anticipation for the arrival of Bob's avatar in the virtual space VS10.

As a more complex example, Alice's avatar may use binoculars to explore distant parts of the virtual world. As such, the peer server 18-1 would need to determine the focal point of the binoculars, discover the peer server hosting the corresponding virtual space, and subscribe to visual message types and event messages from that virtual space. The focal point of the binoculars now defines the AOI for Alice's avatar with respect to those message types. Assume that Alice is looking southeast and the focal point of the binoculars is in the virtual space VS16. This may lie outside of the normal AOI. Thus, in one embodiment, the peer server 18-1 may issue, for example, a vector addressed subscription message in the direction of the peer server 18-16. The subscription message may be vector addressed by, for example, defining the scope(s) of the subscription record(s) as the focal point of the binoculars. As such, the peer servers 18-4 and 18-11 simply update their routing tables and forward the subscription message on to the peer server 18-16. When the peer server 18-16 receives the subscription message, it updates its routing table and routes the desired message types back to the peer server 18-1. Alternatively, the peer server 18-16 may establish a direct connection to the peer server 18-1.

Now, if Alice turns in the clockwise direction still looking through the binoculars, the peer server 18-1 may predict that the focal point will soon be looking at the virtual space hosted by the peer server southeast of the virtual space hosted by the peer server 18-16. As such, the peer server 18-1 may issue a predictive vector addressed subscription message to the peer server 18-17. The predictive vector addressed subscription message may be for all concerned message types or only for content message types since content message types typically take the most time to transfer. In an alternative embodiment, the peer server 18-1 may instruct the peer server 18-16 to issue the predictive vector addressed subscription message to the peer server 18-17.

Another feature that may be provided is specifically addressed ad/sub messages. While this is discussed above with respect to the binoculars example, there are other scenarios where specifically addressed ad/sub messages may be desirable. For example, if two users are interacting via a social communication session such as a teleconference, instant messaging or chat session, or the like, a corresponding ad/sub message may be specifically addressed from the peer server hosting the client of one of the users to the peer server hosting the client of the other user.

FIG. 9 illustrates a block diagram of an exemplary embodiment of the peer server 18-1. However, the following discussion is equally applicable to the other peer servers 18-2 through 18-N. Note that in FIG. 9 dashed lines are used to indicate the flow of messages whereas solid lines are used to indicate the flow of data, control, or the like. The peer server 18-1 generally includes a virtual world engine 24, an interest manager 26, and a peer message handler 28, each of which may be implemented in software, hardware, or a combination thereof. The virtual world engine 24 operates to perform typical virtual world operations such as rendering the virtual space including locally hosted virtual objects 30 at client devices, such as client device 20-X, associated with users having avatars within the virtual space hosted by the peer server 18-1. The peer server 18-1 stores or otherwise has access to virtual space properties 32 such as, for example, terrain and weather information enabling the virtual world engine 24 to render the virtual space.

Interest expressions for the locally hosted virtual objects 30 are registered with the peer server 18-1 and stored in a registered interests database 34. The interest manager 26 operates to aggregate the interest expressions of the locally hosted virtual objects 30 from the registered interests database 34 to provide an interest map for the peer server 18-1. In one embodiment, the interest map includes an entry for each message type produced by one or more of the locally hosted virtual objects 30, where each entry includes the message type, an aggregate scope for the message type, and a listing of virtual objects that produce the message type. The interest manager 26 generates the aggregate scope for each message type produced by one or more of the locally hosted virtual objects 30 by aggregating or combining the auras of those virtual objects for the message type from their interest expressions. The interest map also includes an entry for each message type consumed by one or more of the locally hosted virtual objects 30, wherein each entry includes the message type, an aggregate scope for the message type, and a listing of virtual objects that consume the message type. The interest manager 26 generates the aggregate scope for each message type consumed by one or more of the locally hosted virtual objects 30 by aggregating or combining the AOIs of those virtual objects for the message type from their interest expressions.

The peer message handler 28 includes a message receiver 36 that receives messages from the neighboring peer servers 18-2 through 18-7 of the peer server 18-1. Note that messages from the client 20-X may also be handled by the message receiver 36 and then routed to the virtual world engine 24. Alternatively, the messaging to and from the client 20-X may be handled by a separate client message receiver. An ad/sub message processing and propagation function 38 operates to process and, if appropriate, propagate ad/sub messages received from its neighboring peer servers 18-2 through 18-7 via the message receiver 36 and to update routing table 40 in the manner described above. In addition, the ad/sub message processing and propagation function 38 operates to generate and send ad/sub messages originating at the peer server 18-1 based on the interest map and further update the routing table 40 in the manner described above in order to establish message flow paths for messages produced and consumed by the locally hosted virtual objects 30.

A message routing function 42 operates to route ad/sub messages originating from the peer server 18-1 or further propagate ad/sub messages received by the peer server 18-1 based on the routing table 40. In addition, the message routing function 42 operates to route messages produced by the locally hosted virtual objects 30 to one or more of the neighboring peer servers 18-2 through 18-7 that have expressed an interest in those message types in response to the ad/sub message originating from the peer server 18-1. The message routing function 42 also operates to route messages received from the neighboring peer servers 18-2 through 18-7 according to the routing table 40. More specifically, the routing table 40 is maintained such that messages from the neighboring peer servers 18-2 through 18-7 of message types of interest to the locally hosted virtual objects 30 are routed to the locally hosted virtual objects 30. In addition, messages from, for example, the neighboring peer server 18-2 of message types of interest to others of the neighboring peer servers 18-3 through 18-7 are routed to those peer servers. The messages from the message routing function 42 are sent to the desired ones of the peer servers 18-2 through 18-7 by a message sender 44.

FIG. 10 illustrates a further optimization of the message propagation system of the present invention. In this example, a virtual object, or blocking virtual object, within the virtual space VS4 hosted by the peer server 18-4 blocks the line of sight between Alice's avatar and all or at least a portion of the virtual spaces VS10, VS11, and VS15-VS17, thereby creating a blocked, or affected, area (A) of the virtual world wherein at least certain message types are irrelevant. The blocking object may be, for example, a large wall blocking the line of sight between Alice's avatar and Bob's avatar but not the line of sight between Alice's avatar and Charles's avatar. As such, in this example, the peer server 18-4 generates and effects application of one or more filter rules such that, for example, visual messages related to Alice's avatar or messages related to the movement of Alice's avatar are routed to the peer server 18-12 hosting the virtual space VS12 where Charles's avatar is located but are filtered before reaching the client associated with Bob's avatar. With respect to Bob's avatar, the peer server 18-4 may filter the messages related to Alice's avatar received from the peer server 18-1 such that the messages are not routed to the peer server 18-11 or append a filter rule to the messages such that they are filtered by the peer server 18-11 and not routed to the client associated with Bob's avatar. With respect to Charles's avatar, if the message flow path is via the peer server 18-4, the peer server 18-4 may apply the filter rule or append the filter rule to the messages such that the messages related to Alice's avatar are propagated to the peer server 18-12, which in turn provides the messages to the client associated with Charles's avatar. However, if the message flow path from the peer server 18-1 to the peer server 18-12 is via the peer server 18-5, the peer server 18-4 may provide a filter rule for the message to the peer server 18-12 in response to some triggering event such as, for example, receiving the message from the peer server 18-1. The peer server 18-12 may then apply the filter rule and, in this case, determine that the messages are to be routed to the client associated with Charles's avatar.

Note that the blocking virtual object may be a static virtual object such as a wall or building or a mobile object such as a train or automobile. Further, while a virtual object is used for the example above, filtering may be performed as a result of any properties of the virtual space or information related to the state of the virtual space. As used herein, the properties of the virtual space may include, for example, the terrain of the virtual space, weather conditions within the virtual space, or the like. The state of the virtual space may include, for example, information regarding static and mobile virtual objects within the virtual space and the like. Using the peer server 18-4 as an example, the peer server 18-4 may generate and apply filters based on virtual objects within the virtual space VS4 and/or properties of the virtual space VS4 such as the terrain of the virtual space VS4, weather conditions within the virtual space VS4, or the like. For example, the terrain of the virtual space VS4 may include a mountain or mountain range blocking visibility. As another example, the weather conditions within the virtual space VS4 may including fog blocking visibility. It should also be noted that visibility is used herein as an example because it is easily understood. However, the present invention is not limited thereto. The peer servers 18-1 through 18-N may filter any type of message affected by virtual space properties, the state of the virtual space, or the like.

Further note that the affected area (A) may change based on the three-dimensional location of the source, which in this case is Alice's avatar. More specifically, if the blocking virtual object is a 10-foot tall wall, the affected area (A) will change if Alice's avatar is elevated by, for example, climbing a ladder. Similarly, if Alice's avatar is flying a kite having the same X and Y coordinates but a different height, the affected area (A) is different for the kite than for Alice's avatar.

While the discussion herein focuses on filter rules generated based on the state or properties of a virtual space, the present invention is not limited thereto. For example, the filter rules may alternatively be user-defined.

FIG. 11 illustrates the operation of the peer server 18-4 (FIG. 10) to filter messages based on the state and/or the properties of its virtual space VS4 according to one embodiment of the present invention. First, the peer server 18-1 establishes default message flow paths for messages produced by virtual objects, such as Alice's avatar, within the virtual space VS1 hosted by the peer server 18-1 (step 500). Preferably, the peer server 18-1 establishes the default message flow paths by issuing an ad/sub message, as discussed above. However, the present invention is not limited thereto. Next, the peer server 18-1 receives a message from the client associated with Alice's avatar (step 502). In one embodiment, the message includes information identifying the message type of the message, the coordinates of the virtual object that produced or otherwise triggered the message, a reference to the virtual object that produced or otherwise triggered the message, an indicator as to whether the message is a repetitive message, information regarding any real-time constraints for the message, and a maximum scope of the message. The message may be, for example, an avatar movement event. The peer server 18-1 then routes the message to one or more of its neighboring peer servers 18-2 through 18-7 according to the default message flow path for the message type (step 504). In this example, the peer server 18-1 routes the message to the peer server 18-4.

The peer server 18-4 receives the message from the peer server 18-1 (step 506). In response, the peer server 18-4 identifies one or more filter rules for the message (step 508) and effects application of the one or more filter rules to the message (step 510). The peer server 18-4 generates the filter rules based on the state of the virtual space VS4 hosted by the peer server 18-4; the properties of the virtual space VS4 hosted by the peer server 18-4; coordinates or other information identifying the location of the producer or source of the message, which in this example is Alice's avatar; the scope of the message; and optionally knowledge of the virtual world such as the sizes and shapes of the virtual spaces in the virtual world or a subset thereof, or any combination thereof. The filter rules may be generated proactively or in response to receiving the message. The peer server 18-4 may directly apply the filter rules by, for example, combining the filter rules and the routing rules for the default message path to generate a filtered message flow path. Alternatively, the peer server 18-4 may attach the filter rules to the message and propagate the message according to the default message flow path. The attached filter rules may then be applied by peer servers in receipt of the message.

While the discussion herein focuses on generating the filter rules in response to receiving a message, the present invention is not limited thereto. For example, the peer server 18-4 may additionally or alternatively generate the filter rules proactively. More specifically, either automatically or in response to an ad/sub message, the peer server 18-4 may proactively generate filter rules. In the case of an ad/sub message, the peer server 18-4 may, for each neighboring peer server in the resultant message flow paths, generate one or more filter rules. Note that multiple filter rules may be desired for each message type with respect to each of the neighboring peer servers because the affected area (A) may vary depending on the location of the source of the message.

FIGS. 12A-12D illustrate the process of FIG. 11 with respect to the example of FIG. 10 according to one embodiment of the present invention. FIG. 12A illustrates the default message flow paths for messages related to Alice's avatar. In general, according to the default message flow path, the messages are routed from the peer server 18-1 to the peer server 18-4, which in turn routes the messages to the peer servers 18-11 and 18-12. The peer servers 18-11 and 18-12 then route the messages to the clients associated with the avatars of Bob and Charles, respectively. Note that the peer servers 18-11 and 18-12 may further propagate the message as dictated by the default message flow path for the message.

FIG. 12B illustrates the message flow path after filtering according to one embodiment of the present invention. In general, in response to receiving the message from the peer server 18-1, the peer server 18-4 identifies one or more filter rules for the message. The filter rules for the message may be generated in response to receiving the message or selected from a set of previously established filter rules. The previously established filter rules may be filter rules established in response to previous messages or filter rules established by the peer server 18-4 proactively.

More specifically, in one embodiment, the peer server 18-4 generates one or more filter rules for each of its neighboring peer servers 18-3, 18-5, and 18-10 through 18-12, or at least the ones of the neighboring peer servers 18-11 and 18-12 to which the peer server 18-4 is to propagate the message according to the default message flow path, in response to receiving the message. The peer server 18-4 may first identify the blocked, or affected, area (A) of the virtual world. Then, in one embodiment, the peer server 18-4 has knowledge of at least a size and shape of the virtual spaces hosted by the peer servers 18-1 through 18-N, or at least a relevant subset thereof, and the default message flow path for the message. As such, the peer server 18-4 can determine, for each of the neighboring peer servers 18-11 and 18-12 in the default message flow path, whether the virtual space of the neighboring peer server 18-11, 18-12 and the virtual spaces hosted by any subsequent peer servers in the default message flow path fall entirely within the affected area (A). In this example, the virtual space VS11 hosted by the peer server 18-11 is entirely within the affected area (A) and the default message flow path ends at the peer 18-11. As such, the peer server 18-4 generates a rule for the peer server 18-11 stating that messages of the corresponding message type originating from the location or near the location of Alice's avatar identified in the message are not to be propagated to the peer server 18-11. In contrast, the entire virtual space VS12 of the peer server 18-12 is not within the affected area (A). As such, the peer server 18-4 may provide a filter rule to the peer server 18-12 identifying the affected area (A) or a portion of the affected area (A) relevant to the peer server 18-12 and optionally the location of Alice's avatar or a range of source locations to which the filter rule is applicable. The filter rule may be attached or appended to the message or sent separately. The peer server 18-12 then applies the filter rule to determine whether to route the message to the client associated with Charles's avatar. The peer server 18-12 may store the filter rule locally and use the filter rule to filter future messages of the corresponding message type from the same location or near the same location.

In another embodiment, the peer server 18-4 does not necessarily know anything about the size and shape of the virtual spaces in the virtual world or about the default message flow path other than its own routing rules. As such, rather than directly applying the filter rule, the peer server 18-4 may send the filter rule for the message to the neighboring peer servers 18-11 and 18-12 in the default message flow path. The filter rule may be appended to the message or provided separately. For example, the filter rule may identify the affected area (A) or a portion of the affected area (A) relevant to the peer servers 18-11 and 18-12 and optionally the location of Alice's avatar or a defined range of source locations to which the filter rule is applicable. Note that while the filter rule provided to the peer server 18-11 may be the same as the filter rule provided to the peer server 18-12, the present invention is not limited thereto. For example, different filter rules may be provided to the peer servers 18-11 and 18-12 if different portions of the blocked area are relevant to the peer servers 18-11 and 18-12. Based on the filter rule provided to the peer server 18-11, the peer server 18-11 determines whether to route the message to the client associated with Bob's avatar. In this example, the message is filtered and therefore not routed to the client associated with Bob's avatar. In a similar fashion, based on the filter rule provided to the peer server 18-12, the peer server 18-12 determines whether to route the message to the client associated with Charles's avatar. In this example, the message is not filtered and is therefore routed to the client associated with Charles's avatar. It should be noted that if the default message flow paths extend beyond the peer servers 18-11 and 18-12, the peer servers 18-11 and 18-12 propagate the message and the filter rule.

FIG. 12C illustrates a scenario where the exemplary blocking virtual object is located at a different position within the virtual space VS4, thereby changing the affected area (A) of the virtual world. As a result, both Bob's avatar and Charles's avatar are located within the affected area (A). Regarding Bob's avatar, the peer server 18-4 may directly apply a filter rule stating that the message is not to be propagated to the peer server 18-11. Alternatively, the peer server 18-4 may append the filter rule to the message and send the message including the filter rule to the peer server 18-11 or send the message and the filter rule for the message to the peer server 18-11 separately. Regarding Charles's avatar, in one embodiment, the peer server 18-4 determines that part of the virtual space VS12 hosted by the peer server 18-12 is within the affected area (A). As such, the peer server 18-4 provides the filter rule for the message to the peer server 18-12. Again, the filter rule may be appended to the message or sent separately. In response, the peer server 18-12 applies the filter rule to the message. Since Charles's avatar is within the blocked area in this example, the peer server 18-12 applies the filter rule such that the message is not routed to the client associated with Charles's avatar.

FIG. 12D illustrates a variation where the default message flow path for messages from Alice's avatar to Charles's avatar is through the peer server 18-5 rather than the peer server 18-4. Thus, in this example, the blocking virtual object is not within the virtual space of any one of the peer servers 18-1, 18-5, and 18-12 in the default message flow path between the two avatars. In order to perform filtering in this scenario, the peer server 18-4 may provide the filter rule for the message to the peer server 18-12 in response to a triggering event, which in this example is receiving the message from the peer server 18-1. As another example, the triggering event may be a change in the state or properties of the virtual space hosted by the peer server 18-4 that results in the generation of a new filter rule or an updated filter rule. Thus, in response to receiving the message from the peer server 18-1, the peer server 18-4 may propagate the filter rule for the message to one or more of peer servers, such as the peer server 18-12, that may need the filter rule. Note that the filter rule may be a filter rule that is specific to the message or a filter rule that applies to one or more message types. The peer server 18-12 then filters the messages from Alice's avatar such that they are not routed to the client associated with Charles's avatar.

FIG. 13 is a block diagram of the peer server 18-1 implementing the message filtering scheme according to one embodiment of the present invention. Note that this discussion is equally applicable to the other peer servers 18-2 through 18-N. In general, the peer server 18-1 is substantially the same as the peer server 18-1 illustrated in FIG. 9. However, in this embodiment, the peer message handler 28 further includes a Relevancy Determination Subsystem (RDS) 46, filter rules 48, and a combiner function 50. In operation, the peer message handler 28 generates filter rules. While in one embodiment, the peer message handler 28 may proactively generate the filter rules, in this embodiment, the message receiver 36 interacts with the RDS 46 to generate filter rules for messages in response to receiving the messages. Once generated, the filter rules may be persisted and used to filter subsequent messages to which they are applicable. The combiner function 50 operates to combine the routing rules for a received message from the routing table 40 and any filter rules for the message to provide combined rules. The message routing function 42 then routes the messages based on the combined rules.

FIGS. 14A-14C are a more detailed illustration of the operation of, for example, the peer server 18-4 to identify and effect application of filter rules to messages according to one embodiment of the present invention. First, the peer server 18-4 receives a message (step 600) and determines whether the message has an attached filter rule (step 602). If not, the peer server 18-4 proceeds to step 610. If so, the peer server 18-4 queries the RDS 46 to determine whether the attached filter rule is relevant to the peer server 18-4 (step 604). Based on a response from the RDS 46, the peer server 18-4 determines whether the attached filter rule is relevant to the peer server 18-4 (step 606). If not, the peer server 18-4 proceeds to step 610. If so, the peer server 18-4 adds the attached filter rule to local filter rules for the peer server 18-4 (step 608).

The peer server 18-4 then determines whether the message is specifically addressed to the peer server 18-4 and not from an associated client (step 610). If so, the process proceeds to step 644 (FIG. 14C). If not, the peer server 18-4 determines a message type of the message and/or some other criteria that may be used to identify appropriate filter rules for the message (step 612). Preferably, the message type is included within the message. Alternatively, if the message does not include the message type, the message may be analyzed to determine the message type. The peer server 18-4 then identifies a next neighboring peer server in the default message flow path for the message (step 614). In the first iteration, the next neighboring peer server is a first neighboring peer server. As an example, the first neighboring peer server may be the peer server 18-11. The peer server 18-4 then identifies a filter rule, if any, applicable to the message for the neighboring peer server 18-11 (step 616). The peer server 18-4 then determines whether a filter rule applicable to the message for the neighboring peer server 18-11 exists (step 618). In this embodiment, the peer server 18-4 generates the filter rules in response to receiving messages. In one embodiment, the peer server 18-4 maintains at least one filter rule for each preceding peer server and succeeding peer server combination. Note that the affected area (A) of the virtual world may vary relative to the location of the source of the message to be filtered. As such, for each preceding peer server, the peer server 18-4 may include a separate filter rule for each of a number of source locations or ranges of source locations. For example, looking at the peer server 18-1 as the preceding peer server and the peer server 18-11 as the succeeding peer server, the peer server 18-4 may generate separate filter rules for each of a number of locations or ranges of locations within the virtual space VS1 hosted by the peer server 18-1. Thus, the peer server 18-4 attempts to identify a filter rule for the message by attempting to identify a filter rule from the set of filter rules for the neighboring peer server 18-11 applicable to the location of the source of the message.

If a filter rule does not exist for the message with respect to the neighboring peer server 18-11, the process proceeds to step 622 (FIG. 14B). If a filter rule does exist, the peer server 18-4 determines whether the filter rule needs to be updated (step 620, FIG. 14B). The peer server 18-4 may desire to update the filter rule as a result of movement of virtual objects, changes in the properties of the virtual space VS4, or the like. In addition or alternatively, the peer server 18-4 may desire to update the filter rule periodically. If the filter rule does not need to be updated, the process proceeds to step 630. Alternatively, if a similar message has previously been propagated to the neighboring peer server 18-11 based on the filter rule, a flag or other indicia may be stored to indicate whether the filter rule was attached to the message or combined with the default routing rule for the message. As such, the process may proceed to step 632 or 640 based on the flag. If the filter rule does need to be updated, the peer server 18-4 queries the RDS 46 of the peer server 18-4 (step 622). In one embodiment, the query includes the message, the location of the neighboring peer server 18-11, and the scope of the message. Based on this information and known virtual objects and/or properties of the virtual space, the RDS 46 identifies the affected area (A) of the virtual world in which the message is not relevant due to the state and/or properties of the virtual space VS4 hosted by the peer server 18-4. The RDS 46 then determines whether the message is relevant to the neighboring peer server 18-11. The message is relevant to the neighboring peer server 18-11 when the affected area (A) does not include any of the virtual space VS11 hosted by the peer server 18-11 or any of the virtual spaces hosted by subsequent peer servers in the default message flow path of the message. The message is not relevant or potentially not relevant when the affected area includes all or a portion of the virtual space VS11 hosted by the neighboring peer server 18-11 or the virtual spaces hosted by subsequent peer servers in the default message flow path.

Based on a response from the RDS 46, the peer server 18-4 determines whether the message is relevant to the neighboring peer server 18-11 (step 624). If so, the peer server 18-4 updates the filter rule such that the filter rule is null (step 626). Alternatively, the peer server 18-4 may delete the filter rule or otherwise deactivate the filter rule. If the message is not relevant or potentially not relevant, the peer server 18-4 generates or updates the filter rule for the message based on the response from the RDS 46 (step 628). In one embodiment, the response from the RDS 46 provides sufficient information to enable the peer server 18-4 to generate or update the filter rule. For example, the response from the RDS 46 may identify the affected area (A) or a portion of the affected area (A) relevant to the neighboring peer server 18-11. Note that the filter rule may be stored or persisted at the peer server 18-4. The filter rule may then be used by the peer server 18-4 to filter future messages of the corresponding message type that originated at or near the same location.

At this point, the peer server 18-4 determines whether to attach the filter rule to the message or to apply the filter rule directly (step 630). For example, if the virtual space VS11 of the neighboring peer server 18-11 and the virtual spaces of any peer servers downstream of the neighboring peer server 18-11 in the default message flow path are entirely within the affected area (A), the peer server 18-4 may decide to apply the filter rule directly to the message. Otherwise, the peer server 18-4 may decide to attach the filter rule to the message.

If the peer server 18-4 decides not to attach the filter rule to the message and to apply the filter rule directly, the peer server 18-4 combines the routing rule for the message from the default message flow path and the filter rule for the message to provide a combined rule (step 632) and propagates the message based on the combined rule (step 634). If the peer server 18-4 decides to attach the filter rule to the message, the peer server 18-4 generates a remote filter rule corresponding to the filter rule (step 636), attaches the remote filter rule to the message (step 638), and propagates the message including the remote filter rule for the message to the neighboring peer server 18-11 according to the default message flow path for the message (step 640). Step 636 is optional. The filter rule, rather than a generated filter rule, may alternatively be attached to the message. Note that in an alternative embodiment, the peer server 18-4 may provide the filter rule to the neighboring peer server 18-11 separately from the message. The peer server 18-11 then filters the message based on the filter rule. Note that the peer server 18-4 may check for a filter rule attached to the message. If a filter rule is attached to the message, the peer server 18-4 may consider the filter rule when routing the message or add its own filter rule to the message such that the message includes multiple attached filter rules.

At this point, the peer server 18-4 determines whether it has reached the last neighboring peer server to receive the message according to the default message flow path for the message (step 642). If not, the peer server 18-4 returns to step 614 (FIG. 14A) to repeat the process for the next neighboring peer server. Once the last neighboring peer server is reached, the peer server 18-4 determines whether the message is relevant to itself (step 644, FIG. 14C). If not, the peer server 18-4 optionally unsubscribes to the message type (step 648). If so, the peer server 18-4 processes the message and, if applicable, provides the message to the client associated with Bob's avatar for rendering (step 650). More specifically, the peer server 18-4 applies any attached filter rules and any additional filter rules for the message to determine whether the message is to be provided to the client associated with Bob's avatar. If so, the message is provided to the client associated with Bob's avatar where the message is rendered. At this point, the process returns to step 600 (FIG. 14A).

FIG. 15 illustrates the operation of the RDS 46 according to one embodiment of the present invention. To continue the example above, this discussion focuses on the RDS 46 of the peer server 18-4. First, the RDS 46 receives a request from another subsystem of the peer server 18-4 such as, for example, the message receiver 36 (step 700). The RDS 46 then determines whether the request is a relevancy determination query (step 702). The relevancy determination query is provided to the RDS 46 when generating a filter rule in order to determine whether a received message is relevant to a particular neighboring peer server such as, for example, the neighboring peer server 18-11 or to the local peer space hosted by the peer server 18-4.

If so, the RDS 46 determines the relevancy of the message by determining whether the state of the virtual space VS4 hosted by the peer server 18-4, properties of the virtual space VS4 such as the terrain and weather conditions, or the like affect the message such that it is irrelevant to the neighboring peer server 18-11 and any subsequent peer servers in the default message flow path (step 704). The RDS 46 then returns results of the determination to the requesting subsystem (step 706). In general, if the message is irrelevant to the virtual space VS11 of the neighboring peer server 18-11 and the virtual spaces of any peer servers downstream of the neighboring peer server 18-11 in the default message flow path, the results indicate that the message is irrelevant. Otherwise, the results indicate that the message is relevant or at least potentially relevant to the virtual space VS11 of the neighboring peer server 18-11 and/or the virtual spaces of any downstream peer servers in the default message flow path. If the message is potentially relevant, the results also include information for generating a filter rule to attach to or provide in association with the message. For example, the information may define an affected area of the virtual world in which the message is irrelevant or a portion of the affected area that is relevant to the neighboring peer server 18-11. The results may also indicate whether the message is relevant or irrelevant to the local virtual space hosted by the peer server 18-4. The requesting subsystem, which may be the message receiver 36, then generates a filter rule for the message based on the results.

Returning to step 702, if the request is not a relevancy determination query, the RDS 46 then determines whether the request is a request to update the filter rules in response to an update to the properties or state of the virtual space (step 708). If so, the RDS 46 updates existing filter rules affected by the update and, optionally, proactively generates filter rules resulting from the update (step 710). If not, the RDS 46 determines whether the request is a request to determine the relevancy of a remote filter or filter rule attached to a received message (step 712). If not, the process ends (step 714). If so, the RDS 46 then determines whether any of the virtual space VS4 hosted by the peer server 18-4 is affected by the remote filter (step 716) and whether any neighboring peer servers are affected by the remote filter (step 718). The RDS 46 then returns results identifying whether the remote filter affects any of the virtual space VS4 and whether the remote filter affects any of the neighboring peer servers (step 720). If so, the remote filter is added to the filter rules of the peer server 18-4. The remote filter may also be propagated to one or more neighboring peer servers or downstream peer server.

FIGS. 16A and 16B illustrate the operation of the peer server 18-4 wherein the filtering scheme is applied to ad/sub messages according to another embodiment of the present invention. First, in this example, the peer server 18-1 generates and issues an ad/sub message (step 800). The peer server 18-4 receives the ad/sub message (step 802) and identifies filter rules, if any, for the message types identified in the ad/sub message (step 804). If the filter rules already exist, the peer server 18-4 identifies the applicable filter rules. Otherwise, the peer server 18-4 generates filter rules for the ad/sub message. More specifically, in one embodiment, for each advertisement record, the peer server 18-4 may generate one or more filter rules. Note that different filter rules may be generated for different source locations or ranges of locations within the virtual space VS1 hosted by the peer server 18-1. These filter rules may be combined to provide a corresponding filter rule for the advertisement record to be applied when propagating the ad/sub message. Alternatively, the filter rules may be appended to the ad/sub message or propagated in association with the ad/sub message. The filter rules may then be used by the receiving peer servers when establishing the message flow paths. In a similar fashion, for each subscription record, the peer server 18-4 may generate one or more filter rules. For example, the peer server 18-4 may determine that messages of a message type identified by a subscription record from the peer server 18-4 or any downstream peer servers in the ad/sub message propagation path are irrelevant to the peer server 18-1 as a result of the properties and/or state of the virtual space VS4 hosted by the peer server 18-4. As such, a filter rule is generated such that the corresponding subscription rule is removed from the ad/sub message before propagating the ad/sub message. Alternatively, the filter rule may be propagated with or in association with the ad/sub message.

Once the filter rules for the ad/sub message are identified, the peer server 18-4 then propagates the ad/sub message based on the combination of the filter rules for the ad/sub message and default routing rules for the ad/sub message (step 806). Alternatively, the filter rules may be attached to the ad/sub message, and the ad/sub message including the filter rules may be propagated according to the default routing rules for the ad/sub message. As a further alternative, the filter rules may be propagated separately from the ad/sub message. Note that the peer server 18-4 may cache the full ad/sub message and thereafter issue an updated ad/sub message to its neighbors if the properties or state of the virtual space VS4 are updated such that messages types previously filtered are now relevant. The peer server 18-4 then receives one or more responses to the ad/sub message (step 808) and updates its routing table based on the responses (step 810). The peer server 18-4 then generates a response to the ad/sub message and provides the response to the peer server 18-1 in the manner discussed above (step 812). The peer server 18-1 receives the response (step 814) and updates its routing table accordingly (step 816). At this point, the message flow paths for messages produced and consumed by virtual objects within the virtual space VS1 hosted by the peer server 18-1 are established.

At some point thereafter, the peer server 18-1 receives a message from a client such as, for example, a message from the client associated with Alice's avatar (FIG. 16B, step 818). The peer server 18-1 then routes the message according to the established message flow path for the message (step 820). The peer server 18-4 receives the message (step 822), optionally identifies a filter rule applicable to the message (step 824), and routes the message according to the established message flow path or optionally routes the message according to a combination of a filter rule for the message and the established message flow path for the message (step 826).

FIG. 17 is a block diagram of the network device 12-1 of FIG. 1 according to one embodiment of the present invention. Note that this discussion is also applicable to other network devices 12-2 through 12-N and 14. In general, the network device 12-1 includes a control system 52. In one embodiment, the peer server 18-1 is at least partially implemented in software and stored in memory 54. However, the present invention is not limited thereto. The peer server 18-1 may be implemented in software, hardware, or a combination thereof. The client 20-1 may also be implemented at least partially in software and stored in the memory 54. However, the present invention is not limited thereto. The network device 12-1 also includes a communication interface 56 communicatively coupling the network device 12-1 to the network 16 (FIG. 1). The network device 12-1 may also include a user interface 58, which may include, for example, a display, speakers, one or more user input devices, and the like.

The present invention provides substantial opportunity for variation without departing from the spirit or scope of the present invention. For example, while the description above focuses on the use of both advertisement and subscription records, the present invention is not limited thereto. As will be apparent to one of ordinary skill in the art, the message propagation paths for messages produced and consumed by virtual objects in the virtual worlds may alternatively be established using only subscription messages, where each of the peer servers 18-1 through 18-N issues only subscription messages identifying message types consumed by virtual objects within its virtual space. As another alternative, only advertisement records may be used to establish the message flow paths where each of the peer servers 18-1 through 18-N issues only advertisement messages identifying message types produced by virtual objects within its virtual space. As another example, while the discussion herein focuses on a P2P virtual world, the present invention is equally applicable to any type of distributed virtual world.

Those skilled in the art will recognize improvements and modifications to the preferred embodiments of the present invention. All such improvements and modifications are considered within the scope of the concepts disclosed herein and the claims that follow. 

1. A method for filtering messages propagated in a distributed virtual world formed by a plurality of peer servers each hosting a virtual space of a plurality of virtual worlds of the distributed virtual world, comprising: receiving, at a neighboring peer server from the plurality of peer servers where the neighboring peer server hosts a first virtual space of the virtual world, a message from a sending peer server from the plurality of peer servers hosting a virtual space neighboring the virtual space hosted by the neighboring peer server in the virtual world; identifying at least one filter rule for the message at the neighboring peer server; and propagating the message based on the at least one filter rule for the message from the neighboring peer server.
 2. The method of claim 1 further comprising providing the at least one filter rule based on at least one of a group consisting of: a state of the virtual space hosted by the neighboring peer server and a property of the virtual space hosted by the neighboring peer server.
 3. The method of claim 1 wherein propagating the message comprises: combining at least one routing rule defining at least one default message flow path for the message and the at least one filter rule to provide at least one combined rule; and propagating the message based on the at least one combined rule.
 4. The method of claim 1 wherein propagating the message comprises: attaching the at least one filter rule to the message; and propagating the message including the at least one filter rule attached thereto based on at least one routing rule defining at least one default message flow path for the message.
 5. The method of claim 1 wherein propagating the message comprises: propagating the message according to at least one routing rule defining at least one default message flow path for the message; and propagating the at least one filter rule in association with the message.
 6. The method of claim 1 wherein identifying the at least one filter rule comprises generating the at least one filter rule in response to receiving the message.
 7. The method of claim 6 wherein generating the at least one filter rule comprises: identifying an affected area of the distributed virtual world in which the message is irrelevant based on a location of a source of the message within the distributed virtual world and at least one of a group consisting of: a state of the virtual space hosted by the neighboring peer server and a property of the virtual space hosted by the neighboring peer server; and generating the at least one filter rule based on the affected area.
 8. The method of claim 1 wherein identifying the at least one filter rule comprises selecting the at least one filter rule from a plurality of stored filter rules.
 9. The method of claim 8 wherein the plurality of stored filter rules were generated in response to receiving a plurality of previous messages.
 10. The method of claim 8 further comprising generating the plurality of filter rules proactively prior to receiving the message.
 11. The method of claim 1 wherein identifying the at least one filter rule comprises, for each further neighboring peer server of the neighboring peer server in a default message flow path of the message: identifying a filter rule for the neighboring peer server; and propagating the message to the further neighboring peer server based on the filter rule.
 12. The method of claim 1 wherein the message is a message flow path setup message resulting in at least one default message flow path for a message type of the message.
 13. The method of claim 12 further comprising: receiving, at the neighboring peer server, a second message from the sending peer server of the message type of the message; and propagating the second message based on the at least one default message flow path for the message type.
 14. The method of claim 12 further comprising: receiving, at the neighboring peer server, a second message from the sending peer server of the message type of the message; identifying at least one additional filter rule for the second message; and propagating the second message based on the at least one default message flow path for the message type and the at least one additional filter rule.
 15. The method of claim 14 wherein propagating the second message comprises: combining at least one routing rule defining the at least one default message flow path for the message type and the at least one additional filter rule to provide at least one combined rule; and propagating the second message based on the at least one combined rule.
 16. The method of claim 14 wherein propagating the second message comprises: attaching the at least one additional filter rule to the second message; and propagating the second message including the at least one additional filter rule attached thereto based on at least one routing rule defining the at least one default message flow path for the message type.
 17. The method of claim 14 wherein propagating the second message comprises: propagating the second message according to at least one routing rule defining the at least one default message flow path for the message type; and propagating the at least one additional filter rule in association with the second message.
 18. The method of claim 1 wherein the at least one filter rule prevents propagation of the message to virtual objects located within at least one affected area of the distributed virtual world wherein the message is irrelevant due to at least one of a group consisting of: a state of the virtual space hosted by the neighboring peer server and a property of the virtual space hosted by the neighboring peer server.
 19. The method of claim 1 wherein the state of the virtual space comprises information identifying virtual objects within the virtual space and locations of the virtual objects within the virtual space.
 20. The method of claim 1 wherein a property of the virtual space comprises at least one of the group consisting of: information defining a terrain of the virtual space and information defining weather conditions within the virtual space.
 21. The method of claim 1 wherein the at least one filter rule is user-defined.
 22. The method of claim 1 further comprising updating the at least one filter rule.
 23. A system comprising: a communication interface communicatively coupling the system to a network; and a control system associated with the communication interface and including a peer server hosting a virtual space of a distributed virtual world formed by a plurality of peer servers including the peer server each hosting a virtual space of the distributed virtual world, the peer server configured to: receive a message from a sending peer server from the plurality of peer servers hosting a virtual space neighboring the virtual space of the peer server in the distributed virtual world; identify at least one filter rule for the message; and propagate the message based on the at least one filter rule for the message.
 24. The system of claim 23 wherein the control system is further configured to provide the at least one filter rule based on at least one of a group consisting of: a state of the virtual space hosted by the neighboring peer server and a property of the virtual space hosted by the neighboring peer server.
 25. The system of claim 23 wherein in order to propagate the message, the peer server is further configured to: combine at least one routing rule defining at least one default message flow path for the message and the at least one filter rule to provide at least one combined rule; and propagate the message based on the at least one combined rule.
 26. The system of claim 23 wherein in order to propagate the message, the peer server is further configured to: attach the at least one filter rule to the message; and propagate the message including the at least one filter rule attached thereto based on at least one routing rule defining at least one default message flow path for the message.
 27. The system of claim 23 wherein in order to propagate the message, the peer server is further configured to: propagate the message according to at least one routing rule defining at least one default message flow path for the message; and propagate the at least one filter rule in association with the message.
 28. The system of claim 23 wherein the peer server is further configured to generate the at least one filter rule in response to receiving the message.
 29. The system of claim 28 wherein in order to generate the at least one filter rule, the peer server is further configured to: identify an affected area of the distributed virtual world in which the message is irrelevant based on a location of a source of the message within the distributed virtual world and at least one of a group consisting of: a state of the virtual space hosted by the neighboring peer server and a property of the virtual space hosted by the neighboring peer server; and generate the at least one filter rule based on the affected area.
 30. The system of claim 23 wherein in order to identify the at least one filter rule, the peer server is further configured to select the at least one filter rule from a plurality of stored filter rules.
 31. The system of claim 30 wherein the plurality of stored filter rules were generated in response to receiving a plurality of previous messages.
 32. The system of claim 30 wherein the peer server is further configured to generate the plurality of filter rules proactively prior to receiving the message.
 33. The system of claim 23 wherein the at least one filter rule prevents propagation of the message to virtual objects located within at least one affected area of the virtual world wherein the message is irrelevant due to at least one of a group consisting of: a state of the virtual space hosted by the neighboring peer server and a property of the virtual space hosted by the neighboring peer server.
 34. The system of claim 23 wherein the at least one rule is user-defined.
 35. The system of claim 23 wherein the control system is further configured to update the at least one filter rule. 